Peace Lilies and True Water Lilies belong to entirely different plant families, indicating a distant botanical relationship. True Water Lilies are members of the family Nymphaeaceae, which is a primitive group of flowering plants (angiosperms). This family is further divided into genera, with Nymphaea being the most common. In contrast, the Peace Lily is a member of the Araceae family, also known as the arum or aroid family. Its scientific name is Spathiphyllum spp. Plants in the Araceae family are characterized by their distinctive inflorescence structure, the spadix and spathe, which is a key identifying feature.
This is the most striking difference between the two plants. True Water Lilies (Nymphaea) are aquatic, obligate hydrophytes. This means they are adapted to live and thrive in water. They are typically rooted in the mud at the bottom of ponds or slow-moving rivers, with their leaves (lily pads) and flowers floating on the surface or held slightly above it. Peace Lilies (Spathiphyllum), however, are terrestrial plants. They are native to the forest floors of tropical regions in the Americas and Southeast Asia, where they grow in rich, moist, well-draining soil. They are popular as shade-tolerant houseplants and cannot survive submerged in water; their roots would quickly rot.
The leaves of these plants are vastly different due to their environments. True Water Lilies have large, round, often notched leaves (lily pads) with a waxy, hydrophobic upper surface that repels water. The undersides are porous and may have sharp spines for protection. Their roots are rhizomes that anchor in underwater substrate. Peace Lilies have lance-shaped or oval, glossy green leaves that grow directly from the soil. They have a typical terrestrial root system. While both have leaves that emerge from a central growing point, the texture, structure, and function are adapted for life in water versus life on land.
Both plants produce flowers, but their structures are fundamentally different. The showy white "flower" of a Peace Lily is not a single flower but an inflorescence. It consists of a central spike called a spadix (covered in tiny, real flowers) and a single, large, white, leaf-like bract called a spathe that surrounds the spadix. True Water Lilies produce a solitary, iconic flower with multiple discrete petals and sepals that can be various colors (white, pink, yellow, blue, etc.). These flowers often open during the day or night, depending on the species, and contain numerous stamens and a compound ovary. They emerge from the underwater rhizome on a separate stalk and float on or rise above the water's surface.
